merge-base.c

   1 #include <stdlib.h>
   2 #include "cache.h"
   3 #include "commit.h"
   4
   5 static struct commit *process_list(struct commit_list **list_p, int this_mark,
   6                                    int other_mark)
   7 {
   8         struct commit *item = (*list_p)->item;
   9
  10         if (item->object.flags & this_mark) {
  11                 /*
  12                   printf("%d already seen %s %x\n",
  13                   this_mark
  14                   sha1_to_hex(posn->parent->sha1),
  15                   posn->parent->flags);
  16                 */
  17                 /* do nothing; this indicates that this side
  18                  * split and reformed, and we only need to
  19                  * mark it once.
  20                  */
  21                 *list_p = (*list_p)->next;
  22         } else if (item->object.flags & other_mark) {
  23                 return item;
  24         } else {
  25                 /*
  26                   printf("%d based on %s\n",
  27                   this_mark,
  28                   sha1_to_hex(posn->parent->sha1));
  29                 */
  30                 pop_most_recent_commit(list_p);
  31                 item->object.flags |= this_mark;
  32         }
  33         return NULL;
  34 }
  35
  36 struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
  37 {
  38         struct commit_list *rev1list = NULL;
  39         struct commit_list *rev2list = NULL;
  40
  41         commit_list_insert(rev1, &rev1list);
  42         commit_list_insert(rev2, &rev2list);
  43
  44         parse_commit(rev1);
  45         parse_commit(rev2);
  46
  47         while (rev1list || rev2list) {
  48                 struct commit *ret;
  49                 if (!rev1list) {
  50                         // process 2
  51                         ret = process_list(&rev2list, 0x2, 0x1);
  52                 } else if (!rev2list) {
  53                         // process 1
  54                         ret = process_list(&rev1list, 0x1, 0x2);
  55                 } else if (rev1list->item->date < rev2list->item->date) {
  56                         // process 2
  57                         ret = process_list(&rev2list, 0x2, 0x1);
  58                 } else {
  59                         // process 1
  60                         ret = process_list(&rev1list, 0x1, 0x2);
  61                 }
  62                 if (ret) {
  63                         free_commit_list(rev1list);
  64                         free_commit_list(rev2list);
  65                         return ret;
  66                 }
  67         }
  68         return NULL;
  69 }
  70
  71 int main(int argc, char **argv)
  72 {
  73         struct commit *rev1, *rev2, *ret;
  74         unsigned char rev1key[20], rev2key[20];
  75
  76         if (argc != 3 ||
  77             get_sha1_hex(argv[1], rev1key) ||
  78             get_sha1_hex(argv[2], rev2key)) {
  79                 usage("merge-base <commit-id> <commit-id>");
  80         }
  81         rev1 = lookup_commit(rev1key);
  82         rev2 = lookup_commit(rev2key);
  83         ret = common_ancestor(rev1, rev2);
  84         if (!ret)
  85                 return 1;
  86         printf("%s\n", sha1_to_hex(ret->object.sha1));
  87         return 0;
  88 }